“skin-bottle.” A “bottle” or container made from animal skin.

[For more on skin-bottles, which were usually made from the skins of goats, see commentary on 1 Sam. 10:3.]

“skin-bottle of milk.” Showing hospitality and going above and beyond what was asked. There may also be a kind of mother image going on, because in Judges 5, Deborah is referred to as a mother and Sisera’s mother is waiting for him to come home.